The following background information is provided to assist the reader to understand the environment in which the invention will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless specifically stated otherwise in this document.
A typical freight train includes one or more locomotives and a plurality of railcars. A pneumatic trainline known as the "brake pipe" is the means by which brake commands are pneumatically conveyed from the lead locomotive to each of the railcars in the train. The brake pipe is essentially one long continuous tube that runs from the lead locomotive to the last railcar. The brake pipe is actually composed of a series of interconnected pipe lengths, with one pipe length secured to the underside of each railcar. As shown in FIG. 1, the pipe length 1 on each railcar is connected at each end to one end of an angle cock 2. (Closing an angle cock 2 prevents air from flowing along the brake pipe, generally designated 5, to any of the railcars located downstream of the closed angle cock.) Each angle cock 2 is connected at its other end to one end of a hose 3, with the other end of the hose being connected to a glad hand 4. When the glad hands of adjacent railcars are coupled together, they form a glad hand coupler--the pneumatic connection that links the pipe lengths of the adjacent railcars. The brake pipe 5 of the train is formed by coupling the glad hand 4 of each railcar to the glad hand of the railcar or locomotive located immediately adjacent to it. It is to the brake pipe 5 that the brake equipment on each railcar connects via a branch pipe 6.
By moving a brake handle located in the lead locomotive, a train operator can control how much, if any, pressure is contained within the brake pipe 5 and thus whether, and to what extent, the train brakes will be applied. The positions into which the brake handle can be moved include release, minimum service, full service, suppression, continuous service and emergency. Between the minimum and full service positions lies the service zone wherein each incremental movement of the brake handle toward the full service position causes the brake pipe pressure to reduce incrementally.
As shown in FIG. 1, the brake equipment on a typical freight railcar includes two storage reservoirs 7/8, one or more brake cylinders 9 and at least one brake control valve 10 such as an ADB, ABDX or ABDW type valve made by the Westinghouse Air Brake Company (WABCO). The brake control valve has a service portion 11 and an emergency portion 12 typically mounted on opposite sides of a pipe bracket 13. The pipe bracket features a number of internal passages and several ports. Each port connects to one of the interconnecting pipes from the railcar such as those leading to the brake pipe, the brake cylinder and the two reservoirs. It is through the ports and internal passages of the pipe bracket 13 that the service and emergency portions 11 and 12 of the brake control valve 10 communicate fluidly with the pneumatic piping on the railcar.
For trains equipped with conventional pneumatic brake systems, for example, it is well known that the pressure level within the brake pipe 5 determines whether the brake control valve 10 will charge the reservoirs or deliver pressurized air previously stored in one or both of these reservoirs to the brake cylinders 9. By changing the pressure within the brake pipe, the brake pipe 5 can be used to convey release, service and emergency brake commands to the brake equipment on each railcar in the train. In response to a release brake command (i.e., when brake pipe pressure is increased to 90 psi on a freight train, for example), the service portion 11 of the brake control valve not only charges the two reservoirs with the pressurized air it receives from the brake pipe 5 but also vents the brake cylinders to atmosphere thereby causing the brakes on the train to release. In response to a service brake command (i.e., when brake pipe pressure is reduced at a service rate), the service portion 11 supplies air from only one of the two reservoirs 7 to the brake cylinders 9 so as to apply the train brakes. How much the brake pipe pressure is reduced, and thus the magnitude of the service brake application, depends on how far the brake handle is moved towards the full service position. In response to an emergency brake command (i.e., when the brake pipe pressure is reduced to zero at an emergency rate), the emergency portion 12 of the brake control valve supplies air from both reservoirs 7 and 8 to the brake cylinders 9 so as to apply the train brakes fully. The emergency portion 12 also accelerates the pressurizing of the brake cylinders 9 by venting the brake pipe 5 locally at the railcar.
When pressurized, the brake cylinders 9 convert the pressurized air that they receive from the brake control valve 10 to mechanical force. From the brake cylinders this force is transmitted by mechanical linkage (not shown) to the brake shoes (not shown). The magnitude of the braking force applied to the wheels is directly proportional to the pressure built up in the brake cylinders 9. Forced against the truck wheels and/or disc brakes, the brake shoes are used to slow or stop the rotation of the wheels. For trains equipped with conventional pneumatic brake systems, it is thus the pressure level within the brake pipe 5 that determines whether and to what extent the brakes of the train will be applied.
From the foregoing, it is quite apparent that the operation of the brake equipment on each railcar depends upon the integrity of the brake pipe 5. Especially for long freight trains, the brake pipe 5 must be highly resistant to leaks. The design of the glad hand 4 makes this possible.
The glad hand coupler is gender neutral, i.e., its design does not employ a male-to-female connection arrangement. Consequently, any one glad hand can connect to any other glad hand to form a glad hand coupler. As shown in FIGS. 2 and 3, each glad hand 4 is comprised of a connector body 20 that has a restraining arm 30 and two arcuate projections 31 and 32. Typically cast as a single piece component, the connector body 20 is essentially a pipe whose passage 21 runs from a nipple 22 at one end to a flow port 23 at the other end. The nipple end 22 is designed to connect to the brake pipe hose 3 on the railcar as shown in FIG. 1.
The connector body 20 features a mating surface 24 from which the flow port 23 emerges, with the longitudinal axis of the flow port 23 being essentially perpendicular to the longitudinal axis of the passage 21. Adjacent to the mating surface 24 and within the cylindrical boundary wall 23A that defines the flow port 23 lies an annular recess 25. Into this annular recess 25 snaps a ring-shaped compressible sealing member 26, an outermost part 27 of which extending beyond the mating surface 24 and into the connector slot 28 between the two arcuate projections 31 and 32 of the glad hand 4. The sealing member 26 is typically composed of rubber or other suitable compressible sealing material.
Coupling two glad hands 4 together involves moving the two connector bodies 20 towards one another to an inverted "V" position such that their respective arcuate projections 32 and restraining arms 30 are nearly perpendicular to one another. Once their respective flow ports 23 are juxtaposed and the arcuate projection 32 of one is aligned to engage the arcuate projection 31 of the other, the two glad hands are ready to be rotated together about an axis shared by the centers of the two flow ports 23. Each arcuate projection 31 and 32 has a tapered lead-in groove 33. By rotating the connector bodies 20 from the inverted "V" position towards an upright "V" position, the arcuate projection 32 of one glad hand engages within the groove 33 of the arcuate projection 31 of the other glad hand and vice versa. Consequently, as the opposing projections are engaged, the compressible sealing members 26 of the two connector bodies 20 are forced together. Compressed in this manner, the sealing members 26 not only serve to hold the arcuate projections into their corresponding grooves but also provide the necessary air tight seal. This allows the flow port 23 of the one glad hand to communicate with the flow port 23 of the other glad hand with little or no leakage of air from the brake pipe.
The restraining arm 30 atop each glad hand 4 limits the extent to which the glad hands can be rotated together as the tip 35 of each arm confronts the upper tab 29 of its corresponding arcuate projection 31. Thus, only by rotating the connector bodies 20 in the opposite direction can the two glad hands 4 be disconnected from each other.
Due to the length and disposition of the brake pipe hoses 3 on the vehicles of the train, the glad hands 4 when coupled together lie at an angle relative to the centerline of the adjacent vehicles. Consequently, the glad hand coupler and its two interconnected brake hoses dangle a safe distance above the railway track and thereby avoid contact with the rails, railroad ties, road crossings and other potential obstructions.
The restraining arm 30 of a glad hand also defines a carrier hole 36 to which a bungee cord can be attached. When adjacent vehicles are mechanically uncoupled and pulled away from each other, the two glad hands 4 are designed to automatically rotate in the opposite direction and eventually uncouple as their respective brake hoses 3 become taut. With its other end attached to the mechanical coupler, each bungee cord prevents its glad hand 4 from falling to the railway track when the adjacent vehicles are mechanically uncoupled.
Presently, there is no need to intercept or otherwise disturb the glad hand couplers between the vehicles of a train. At some future date, however, it is anticipated that a device will eventually be developed that, if given access to the brake pipe between the rail vehicles, will allow the brake pipe to be vented at that location during a brake application. By installing one or more of these devices at various points throughout a freight train, the brake pipe could be vented much more rapidly than is otherwise possible with currently known means. Such a device would thus enable the brakes of a train to be applied much faster than is currently possible on many types of trains currently in service. This is especially true of trains equipped with conventional pneumatic brake control systems as the reduction in pressure typically starts at the lead locomotive and takes quite some time to progress along the brake pipe to the last railcar in the train.
Various designs have been proposed for an adapter whose purpose would be to connect between the glad hands and to provide such a device access to the brake pipe between the vehicles of the train. Of the adapters that have been proposed, all have consisted of combinations of existing hardware (e.g., three glad hand fittings connected in a "T" arrangement). The adapters resulting from these proposed designs, however, have proven to be inadequate or inappropriate to the task. The size or arrangement of the parts in these designs have caused excessive twisting or displacement of the brake pipe hoses. For example, these proposed adapters have caused the hoses to kink excessively and the glad hands to which they are connected to dangle precariously close to the railway track where they are more likely to strike rails, railroad ties, road crossings and other potential obstructions. The invention described and claimed below is intended to address these shortcomings.